Crucible treatment of metals



H. KOPPERS. QRUCIBLE TREATMENT oF METALS.

APPLICATION FILED SEPT. 3,' I 920.

Patented N ov. 2, 1920.

l rfi? 4 g la .Il

lof great importance iniuNiTED STATES PATENT OFFICE.

HEINRICH KOPPERS, `OF ESSEN-ON-THE-RUHR, GERMANY, SSIGNOR TO THE KOPPERS DEVELOPMENT CORPORATION, A CORPORHTION OF PENNSYL- VANIA.

CBCIBTE TREATMENT 0F METALS. Y

Specification of VLetters Patent. Patenfged NOV 2, 1920 Application filed September 3, 1920. Serial No. 408,082.

To all whom t may concern:

Be it known that I, HEINRTCH KorrERs, (assignor .to THE KoPrEiis DEVELOPMENT CORPORATION, of Pennsylvania,) a citizen of Germany, residing in Essen-on-the-Ruhr, Germany, have invented a new and useful Improvement in Crucible Treatments of Metals, of which the following is a specification.

This invention relates to the treatment of metals, such as iron and its alloys, in crucibles and has for one of its objects to effect ellicient refining, including desulfurization of the metal and to obtain a high grade product containing a minimum proportion of sulfur.

The presence of sulfur, especially in iron and its alloys, greatly impairs the quality of the metal, when occurring in other than extremely small proportions. ent in iron, sulfur makes the ironA much 'more liable to rust; in fact, the tendency of iron to deteriorate when exposed to atmospheric conditions is augmented bv the presence *of sulfur which constitutes an important factor in promoting such deterioration. In the case of steel, the presence of sulfur not only makes the steel liable to rust, but imparts a brittle quality to the steel making it diflicult to shape and impairing its strength. Consequently, it is y VMythe metallurgical industry to restrict the i'tuantityy of sulfur in such metals as iron and steel to mere traces.

This invention provides a novel 'and improved treatment of the.. metal in a crucible furnace, by which treatment the sulfur content in the product of the crucible is limited to mere traces which`do not appreciablyimpair the quality of the metal.

The invention has for other objects such other improvements or advantagesin operation and such other advantageous results as may be found vto obtain in thev improved processes' and apparatus hereinafter def,

scribed as illustrative examples.-

In the accompanying drawings, forming and showing,

a preferred for purposes of exemplication,

manner in which-the invention may be embodied and practised, but without limiting the claimed invention specifically to such illustrative linstance or instances:

Figure 1 is a vertical section through a diagrammatic representation of a crucible When presor refining vessel for practising the provements of the present invention; and Fig. 2 is a horizontal section of thevsame 4on the line 2 2 of Fig. 1.

ten iron charged into the chamber 13 passes in small drops, or in the form of a spray, and is uniformly distributed throughout the area of a mass of slag which is charged into the crucible in a superhcated molten state. The slag mass, indicated at 15, stratifies on top of the molten metal stratum 16 in the bottom of the lower chamber 12. The level of the slag stratum 15 is maintained just below the partition 14 by a slag oVer- How duct 17 which fixes the slag level. Immersed in the slag are pieces of incandescent carbon, such as coke, which may be -introduced into the slag lthrough an inlet 18 in the side of the Crucible. The inlet 18 is kept normally closed by means of a plug of any suitable character.

In addition to its neutralizing action on the acidity of the ash contained in the coke, theV lime stone slag stratum has an aflinity for sulfur and such property of the slag" to absorb sulfur is augmented by contact of incandescent carbon which, because of the level maintained by the overflow pipe 17 and the partition 14, dips into the slag Stratum.

The incandescent carbon dipping intof the Superheated molten slag stratum constitutes a reduction medium that liberates elements having a deoxidizing e'ect on the iron. The molten metal discharged in small drops, or in the form of a spray from the bottom of the partition 14, flows downwardly through and is subjected to the prolonged action of the solid incandescent carbon and slag, and during such iiow through the slag stratum a reaction is effected between the basic coinpounds present in the slag and the sulfur contained in the metallic iron, causing sulfur to be absorbed from the iron and to" be relll) action resulting in the formation of calcium.

sulfid and pure iron. The calcium sulfdis soluble in and will be retained by the slag. The importance of the presence ot incandescent carbon is illustrated by the first formula given above inasmuch as the action of' the carbon is first to reduce the calcium oxid to metallic calcium, thereby augmenting' the aflinity of' the slag stratum for absorption of sulfur from the metal which passes through the slag.

ln accordance with the invention, the v'above described factors which augment desulfurization of the iron are maintained continuously in their condition of maximum effect as regards desulfurization, during operation of' the Crucible. In order to effect this result and to secure a maximum desulfurizing effect promoted by the action of the slag and immersed carbon, the invention proy vides for the maintenance of a continuous mass of slag in the lower chamber of the crucible. By the invention the iron obtained contains only small traces of sulfur. The partition 14 keeps the incandescent carbon continuously immersed in the slag to maintain the slag at all times in its condition of maximum Aafiinity for absorption of sulfur. The molten metal is discharged from the bottom of the hearth through an overflow duct 19 which leads first upwardly and thence downwardly to a receiving vessel 20 for the molten metal. The fixed slagr overflow 'duct 17 will determine the height of the slag level in the crucible, whereas the fixed location of the crest 2l of the metal overiow duct 19 will determine the height of molten metal in the crucible, thereby maintaining constant levels both of slag and molten metal in the crucible. ln practice, the relation of' these respective heights may be expressed as follows: the height of the crest of the overflow pipe above the junction with the hearth of the furnace equals the height of the molten metal in the furnace above the junction point of the overflow pipe plus two-sevenths of the height of the slag stratum in the lower chamber of the furnace, assuming that the specific gravity of the slag be two and that of the iron be seven.

The invention as hereinabove set forth may be practised in various ways without departing from the scope-ot the claims hereinafter made.

lt claim:

1. A crucible for the treatment of metals, such as iron or its alloys, comprising: a vessel; a foraminous partition dividing said vesscl into upper and lower compartments, to cause molten metal charged in the upper compartment to flow through the lower compartment in the form of a spray; and means for maintaining the slag and molten metal in the lower compartment respectively at constant levels; substantially as specified.

21 A crucible for the treatment of metals, such as iron or its alloys, comprising: a ves sel; a foraminous partition dividing said vessel into upper and. lower compartments, to cause molten metal charged in the upper compartment to flow through the lower compartment in the form of a spray; and constant-outflow means 'for permitting separate discharge of the slag and metal from said lower compartment; substantially as specified.

3. A crucible for the treatment of metals, such as iron or its allows, comprising: a vessel; a foraminous partition dividing said vessel into upper and lower compartments,`

to cause molten metal charged in the upper compartment to flow through the lower compartment in the form of a spray; and overflow means communicating with said lower compartment.

4. A crucible for the treatment of metals, such as iron or its alloys, comprising: a ves sel; a foraminous partition dividing said vessel into upper and lower compartments', the upper compartment receiving the molten metal and the lower compartment having an inlet for coke, said partition causing dis'- tribution of the molten metal in the form of a spray through the slag stratum in the lower compartment and also maintaining the coke submerged in the slag stratum; and means for maintaining the slag and molten metal in the lower compartment respectively at constant levels; substantially as specified.

5. In the treatment of metals, such as iron or its alloys, a. vessel in which molten slag stratifies on top of the mass of molten metal, means for converting the molten metal, introduced into said vessel, into the form of a spray, for permitting the small particles of metal to pass and be distributed through the slag stratum, and separate outflow means for discharging the metal and slag from said vessel; substantially as specified.

G. 'llhev improved process of refining metals, such as iron and its alloys, which consists in converting the molten metal into the form of a spray, and passing the spray of molten metal through a molten slag stratum having an affinity for sulfur, substantially as specified.

7. The improved process of refining metals, such as iron and its alloys, which consists in converting the molten metal into neef/,vea

the form or" a spray, and uniformly distributing the spray of molten metal through a molten slag stratum having an aflinity for sulfur, substantially as specified.

8. 'lhe improved process of reiining metals, such as iron and its alloys, Which consists in converting the molten metal into the form of a spray, and passing the spray of molten metal through a slag stratum in the presence of incandescent carbon, substantially as specified.

9. The improved process of refining metals, such as iron and its alloys, which consists in converting the molten metal into the form of a spray, and passing the spray ot' molten metal through a slag stratum in which incandescent carbon is submerged, A

substantially as specified.

' l0. rlhe improved process of reiining metals, such as iron and its alloys, which consists in converting the molten metal into the form of a spray, and passing the spray of molten metal through a bath of basic slag in which incandescent carbon is submerged, substantially as specified.

ll. An apparatus for de sulfurizing met als, such as iron and its alloys, comprising: a vessel for containing the metal and slag, over-How means for the metal and slag for maintaining constant levels respectively of the metal and superposed slag, and means for maintaining carbon submerged in the slag and for distributing the molten metal through the slag in the 'orm of a spray.

' HEINRICH KOPPERS. 

